Xanamem® in Adults With Major Depressive Disorder and Impaired Cognition (XanaCIDD)

Key Inclusion Criteria: * Male or female aged 18 to 75, inclusive. * Positive MDD primary diagnosis confirmed by the Mini-International Neuropsychiatric Interview (MINI). * Persistent depressive symptoms as determined by a Hamilton Depression Rating Scale (HAM-D) ≥ 17 at Screening. * Cognitive abilities on a coding test \> 0.5 standard deviations below expected. * Self-reported subjective cognitive dysfunction. * Currently or previously treated with a stable dose of a first- or second-line antidepressant that is approved for the treatment of depression (but not a tricyclic antidepressant, monoamine oxidase inhibitor, or vortioxetine). If on current treatment, dose must be stable for at least 6 weeks. * Smokers are eligible if they are able to comfortably abstain from nicotine for 2 hours prior to scheduled cognitive assessments. * Able to comfortably abstain from caffeine intake for 4 hours prior to scheduled cognitive assessments. * Must provide written informed consent to participate in the trial and be willing and able to comply with the requirements of the protocol and complete all trial visits. Key Exclusion Criteria: * Active suicidal ideation within the previous 3 months * On a tricyclic antidepressant, monoamine oxidase inhibitor, esketamine, or vortioxetine. * A history of clinically diagnosed dementia of any type * Previous clinically significant systemic illness or infection, including test positive COVID-19, within the past 4 weeks prior to Screening * Has a BMI or body weight that will interfere with participation in the trial * Type I or Type II diabetes requiring insulin * Clinically significant ECG abnormalities * Participation in another clinical trial of a drug or device * Trial participants who in the opinion of the Investigator exhibit physical, cognitive, or language impairments of such severity as to adversely affect the validity of the data derived from the neuropsychological tests. * Positive testing for HIV, hepatitis B surface antigen, or hepatitis C antibodies at Screening. * Participants with a history of drug abuse or addiction in the past 2 years * Current use of cannabis/marijuana, or tetrahydrocannabinol-containing medications.